Search Results (5)

Apple pomace represents an important agro-industrial residue with high moisture content and significant environmental burden if improperly managed. This study investigated its thermochemical valorisation into biochar via two processes, followed by comprehensive physicochemical characterization and agronomic evaluation. Elemental analysis revealed carbon enrichment from 47.89% in raw material to 77–78% after the thermal process, evidencing a progressive aromatization. Scanning electron microscopy, Fourier transform infrared spectroscopy, and Raman analysis confirmed a temperature-dependent transition from partially amorphous carbon (400 °C) to more ordered aromatic structures (450 °C), while excessive thermal treatment (550 °C) increased structural defects. ICP-OES revealed an enrichment in thermally stable metals (Fe, Al, Mn) and limited Cd accumulation. Germination assays using Triticum aestivum L. demonstrated that biochar produced at 400 °C significantly improved the germination uniformity and seedling height (14.1 mm), as well as biomass accumulation compared to the control soil sample. The fertilizer addition increased the soluble Na and electrical conductivity (up to 643 µS/cm), potentially inducing transient salinity stress. Soil chemical analysis indicated increased K availability in soils amended with biochar produced at 400 °C, whereas the combination of biochar obtained at 450 °C with fertilizer conducted to elevated concentrations of certain trace metals, mainly Ni and Cr, highlighting the demand for careful monitoring. Overall, the biochar produced at 400 °C yielded to an optimal balance between structural stability, nutrient enrichment, and agronomic performance, evidencing that apple pomace may be a viable feedstock for sustainable biochar production within circular bioeconomy frameworks. Full article

Four biomass residues–rosemary pomace, rosemary cake, grape seed and apple pomace–were torrefied at 250, 350 and 450 °C, and the physical, chemical and structural changes were characterized. The mass and energy yield decreased with increasing torrefaction temperature; the lowest mass (~10.4%) and energy yield (~10.6%) were observed for rosemary cake torrefied at 450 °C. The HHV increased the most for all feedstocks at 350 °C, with rosemary cake reaching a peak value of 36.4 MJ/kg at 350 °C. Ash content increased with temperature due to organic mass loss, while volatiles decreased and fixed carbon increased in most samples. The FTIR spectra showed the progressive loss of hydroxyl, carbonyl and C–O functionalities and the appearance of aromatic C=C bonds, indicating the formation of the biochar. TGA and DTG analyses revealed that the torrefied samples exhibited higher initial and maximum temperatures for decomposition, confirming improved thermal stability. The TGA-FTIR analyses of gas emissions during pyrolysis and combustion showed that the emissions of CO₂, CH₄, NO_x and SO₂ decreased with increasing degree of torrefaction. Overall, 350 °C was optimal to maximize energy density. The results show that agro-industrial residues can be effectively converted into sustainable biofuels, which offer the dual benefit of reducing waste disposal problems and providing a renewable alternative. In practice, such residues could be used for decentralized power generation in rural areas, co-combustion in existing power plants, or as feedstock for advanced bioenergy systems. Full article

In many countries, apple pomace (AP) is one of the most produced types of agri-food waste (globally, it is produced at a rate of ~4 million tons/year). If not managed properly, such bio-organic waste can cause serious pollution of the natural environment and public health hazards, mainly due to the risk of microbial contamination. This review shows that AP can be successfully reused in different industrial sectors—for example, as a source of energy and bio-materials—according to the idea of sustainable development. The recovered active compounds from AP can be applied as preservatives, antioxidants, anti-corrosion agents, wood protectors or biopolymers. Raw or processed forms of AP can also be considered as feedstocks for various bioenergy applications such as the production of intermediate bioenergy carriers (e.g., biogas and pyrolysis oil), and materials (e.g., biochar and activated carbon). In the future, AP and its active ingredients can be of great use due to their non-toxicity, biodegradability and biocompatibility. Given the increasing mass of produced AP, the commercial applications of AP could have a huge economic impact in the future. Full article

Due to its high water and organic contents, management of apple pomace (AP) poses several waste management challenges on the apple juice and cider producing industries. Bioconversion of AP into biogas provides an excellent possibility to reduce the environmental challenge faced in the management of AP waste along with producing renewable energy in the form of methane. This study investigated the effect of carbon-based conductive materials (biochar and graphene) and trace metals supplementation to improve biogas production from AP. The results indicate that supplementation of biochar, trace metals, and graphene significantly improves the biogas production from AP. Trace metal and biochar supplementation at a COD concentration of 6000 mg/L resulted in 7.2% and 13.3% increases in the biogas production, respectively. When trace metals and biochar were supplemented together, the biogas production increased by 22.7%. This synergistic effect was also observed at the COD concentration of 12,000 mg/L. The improvement in the biogas formation was significantly higher for graphene supplemented reactors (27.8%). Moreover, biochar and trace metals supplementation also led to 19.6% and 23.0% increases in the methane yield relative to the reactor fed only with AP, respectively. These results suggest anaerobic digestion supplemented with carbon-based conductive materials and trace metals is a viable option for valorizing apple pomace. Full article

Waste biomass can be used as an alternative source of energy. However, such use requires prior treatment of the material. This paper describes the physicochemical characteristics of biochar obtained by the thermochemical decomposition of six types of agricultural waste biomass: residues from the production of flavored spirits (a pulp of lime, grapefruit and lemon), beetroot pulp, apple pomace, brewer’s spent grain, bark and municipal solid waste (bark, sawdust, off-cuts and wood chips). The biomass conversion process was studied under conditions of limited oxygen access in a reactor. The temperature was raised from 450 to 850 °C over 30 min, followed by a residence time of 60 min. The solid products were characterized in terms of their elemental compositions, mass, energy yield and ash content. The gaseous products from pyrolysis of the biomass were also analyzed and their compositions were characterized by GCMS (Gas Chromatography–Mass Spectrometry). The carbonization process increased the carbon content by, on average, 1.7 times, from an average percentage of 46.09% ± 3.65% for biomass to an average percentage of 74.72% ± 5.36% for biochars. After carbonization, the biochars were found to have a net calorific value of between 27 and 32 MJ/kg, which is comparable or even higher than good-quality coal (eco pea coal 24–26 MJ/kg). The net calorific values show that the volatile products can also be considered as a valuable source of energy. Full article